The 'internet' is global system of interconnected computer networks. Home computers connect to the internet using a router. If you have a wireless router, the PS Vita has its own wi-fi capabilities, and can connect to the internet via your router. There is also a 3g version which can connect via the 3g network, but that needs a sim card and a subscription, like a mobile phone.
The PSVita connects to your wireless router in exactly the same way as your PC and other online devices, and uses your own internet connection to access its online functions such as the browser, PSN store, and online gaming. There is no additional cost for this.
The PSVita does not use UMDs, your games either come on the new PSVita Game Cards, or are downloaded from the PSN.
Capcom hasn't said anything about Resident Evil Revelations being released on the psvita.
A PSVita does not have a router, a router is something you usually get from your internet service provider.
The PSVita is not region locked, a US PSVita can play an EU PSVita game as would be bought in the UK.
Nobody knows, but I can tell you it will probably be out by August 2012
Yes, the PSVita has physical games, small cartridges called PSVita Game Cards. The PSVita has a slot at the top for them.
Yes, the PSVita's screen is HD.
No, at this moment in time, is it not available for PSVita.
Sony hasn't stopped making the PSVita.
No way - psvita is the best, in my opinion.
Yes, the PSVita was released on the 17th of December, 2011.